KRUGMAN: Bernie Sanders 'is becoming a Bernie bro'

Paul Krugman lashed out at Bernie Sanders' newfound criticism of Hillary Clinton in a scathing New York Times column published Friday.

Krugman, a Times columnist and Nobel Prize-winning economist, said Sanders "is starting to sound like his worst followers," after the senator questioned Clinton's qualifications to be president during a Wednesday rally.

"Bernie is becoming a Bernie Bro," Krugman wrote.

He disparaged Sanders for his lack of policy detail on his major Wall Street-related campaign platforms, which is a suggestion Sanders has spent the week fighting off after a much-critiqued Daily News interview.

"Going on about big banks is pretty much all Mr. Sanders has done. On the rare occasions on which he was asked for more detail, he didn't seem to have anything more to offer. And this absence of substance beyond the slogans seems to be true of his positions across the board," Krugman wrote.

Krugman considered the counterpoint: You could argue policy details don't matter, he wrote, as long as your favorite politician "has the right values and character."

But he said Sanders' recent, more personal attacks raise "serious character and values issues" about the candidate. Krugman pointed specifically to what he called surface-level attacks on her Wall Street connections, "dishonest" accusations that she is a "tool" of the fossil fuel industry, and the Wednesday rant about her qualifications for office.

Clinton, who responded to Sanders' brutal Daily News interview by suggesting the senator "hadn't done his homework," was more careful about her word choice, Krugman wrote:

But Mr. Sanders wasn't careful at all, declaring that what he considers Mrs. Clinton's past sins, including her support for trade agreements and her vote to authorize the Iraq war - for which she has apologized - make her totally unfit for office.

This is really bad, on two levels. Holding people accountable for their past is O.K., but imposing a standard of purity, in which any compromise or misstep makes you the moral equivalent of the bad guys, isn't. Abraham Lincoln didn't meet that standard; neither did F.D.R. Nor, for that matter, has Bernie Sanders (think guns).

And the timing of the Sanders rant was truly astonishing. Given her large lead in delegates - based largely on the support of African-American voters, who respond to her pragmatism because history tells them to distrust extravagant promises - Mrs. Clinton is the strong favorite for the Democratic nomination.

Krugman questioned whether Sanders was trying to position himself to "join the 'Bernie of bust' crowd" and refuse to support Clinton in the general election if he's unable to win the nomination. He currently faces a large delegate deficit and long odds.

"If not, what does he think he's doing?" Krugman wrote. "The Sanders campaign has brought out a lot of idealism and energy that the progressive movement needs. It has also, however, brought out a streak of petulant self-righteousness among some supporters. Has it brought out that streak in the candidate, too?"

Sanders, for his part, told CBS' Charlie Rose in a Thursday interview that he would "certainly" support Clinton should she be the November nominee. He added that he only attacked the candidate because she attacked first.

"I'm responding to attacks that are being made against me," Sanders said.